High Evapotranspiration in Urban Areas - A Case Study in Beijing

Abstract:

Urbanization has a significant influence on the local, regional even global hydrologic process, such as runoff generation, drainage, and water consumption. The final water consumption is evapotranspiration into atmosphere, so it is important to estimate the evapotranspiration in urban area. Usually the urban area is considered as an area of low evapotranspiration, but it is challenged by the wet islands effects. In order to make it clear, we estimated the evapotranspiration by water balance based on the hydrology information and water process data of Beijing from 2003 to 2012. The water balance analyses were made in total area and different sub area including mountain area, plain area, urban area and the suburban area. The results show that (1) the average evapotranspiration in Beijing was close to the precipitation so Beijing made limited contribution to the water resources of the Haihe River Basin; (2) the average evapotranspiration in urban area is about 928mm/a, even higher than the evaporation on water surface; (3) the evapotranspiration in urban area controlled by the precipitation and human activities. We can conclude that the evapotranspiration or water consumption in urban area is higher than that in surround area in Beijing.